Method of forming an absorbent article

ABSTRACT

An absorbent article comprising, an absorbent pad having a mass of hydrophilic fibers and a matrix of a comminuted hydrophobic material dispersed in the interfiber spaces defined by the fibers throughout at least a portion of the pad.

This application is a continuation of Application Ser. No. 841,091,filed Oct. 11, 1977, now abandoned, which itself is a continuation ofapplication Ser. No. 669,423, filed Mar. 23, 1976, now abandoned, whichitself is a division of application Ser. No. 603,071, filed Aug. 5, 1973and now U.S. Pat. No. 3,976,074, issued Aug. 24, 1973. U.S. Pat. No.4,069,821, issued Jan. 24, 1978 on application Ser. No. 668,757, filedMar. 22, 1976 is also a division of application Ser. No. 603,071.

BACKGROUND OF THE INVENTION

The present invention relates to absorbent articles, and moreparticularly to disposable absorbent articles.

An assortment of absorbent articles of the disposable type have beenproposed for use in receiving and retaining body fluids, such asdisposable diapers and santiary pads. The articles may have a fluidimpervious backing sheet, a fluid pervious top or cover sheet, and anabsorbent pad between the backing and top sheets to capture the bodyfluids which pass through the top sheet. The pads are commonly made froma fibrous cellulosic material which provides the desired absorbentcharacteristics to the pad.

Although such pads may perform their absorbent function adequately uponreceipt of the first or initial surge or surges of fluid, such as urine,it has been found that absorbency in the pads during subsequent use ofthe articles may be impaired due to the nature of the materials in thepad while in a wet condition. In particular, when the wet cellulosicfibers are placed under loads the fibers are compacted, thus reducingthe interfiber spaces between fibers in the wet pad and compromising theabsorptive capacity of the pad. For example, when a disposable diaper iswet by an infant, the weight placed by the infant on the wet diaper padmay sufficiently compact fibers in the pad such that the totalabsorptive capacity of the pad is reduced.

Of course, a solution to the absorbency problem would be satisfactory ifthe over-all cost of the disposable article is not significantlyincreased, and would be particularly desirable if, in fact, the costtime of the article to the consumer is decreased. As will be seen below,a solution of a problem related to the manufacture of such articles alsoresolves the difficulty associated with absorbency of the articlesduring use.

The materials normally utilized in making the absorbent articles, e.g.disposable diapers, are described as follows. The fluid imperviousbacking sheets are made of a thermoplastic material, such aspolyethylene, the fluid pervious top sheets are commonly made of afibrous nonwoven material having a hydrophobic binder, while theabsorbent pads are made of an absorbent cellulosic material, such aswood fluff. The diapers are usually provided with tape fasteners forsecuring the diapers about infants. Such fasteners have a backingcommonly made of a thermoplastic or paper material and an adhesivecoating on one surface of the fastener backing. It will be seen that thebasic components of the diaper are products of natural resources and arecostly, viz., trees and oil, and are likely to be so in the future.Hydrocarbon feed stuffs from oil are utilized to make the backingsheets, and possibly the adhesive and backings of the tape fasteners,while fibers formed from appropriate wood pulp are utilized to make theabsorbent pads, the top sheets, and possibly the fastener backings ofthe diapers.

Yet the manufacture of such articles, which have come into every dayuse, is attendant with waste resulting in disposal of large quantitiesof such valuable materials. For example, when manufacture of sucharticles is initiated on a machine, a substantial amount of thematerials may be utilized before a satisfactory article is obtained forpackaging and sale, and the initial portion of such materials producedduring the setup procedure would normally be discarded as waste.Additional waste materials may be accumulated while the machine is notfunctioning properly, during unscheduled stops of the machine, afterbreakage of materials utilized in making the articles, or during changesof raw material sources supplied to the machine.

In each case, the rejected materials have been discarded or destroyed inthe past as waste, resulting in loss of valuable natural resources. Forexample, the waste materials may be utilized for purposes of packing,resulting in minimal use of the materials relative their value.Alternatively, the materials may be burned or used as land fill, wherepermitted, which is wasteful and generally undesirable from anecological point of view.

SUMMARY OF THE INVENTION

A principal feature of the present invention is the provision of animproved absorbent article and a method of making such an article in aninexpensive manner.

The article of the present invention comprises, an absorbent pad havinga mass of hydrophilic fibers and a matrix of a comminuted hydrophobicmaterial dispersed in interfiber spaces defined by the fibers throughoutat least a portion of the pad.

A feature of the present invention is that the hydrophobic materialsprovide a greater wet resiliency to the pad.

Another feature of the invention is that the hydrophobic materials helpmaintain interfiber spaces between the hydrophilic fibers of the padopen under loads and during longer periods of time.

Thus, a feature of the present invention is that the hydrophobicmaterials in the absorbent pad enhance the absorptive capacity of thepad when wet and compressed during use.

A feature of the invention is that a portion of the hydrophilic fibersmay be made from a waste absorbent article.

Yet another feature of the present invention is that the hydrophobicmaterial may be made from a waste absorbent article.

Another feature of the present invention is that the absorbent pad maybe made from waste absorbent articles, thus reducing the cost of thearticle to the consumer.

A feature of the invention is that the hydrophobic material in the padmay be formed from fused thermoplastic materials.

A further feature of the invention is that the fused materials enhancethe effective fiber length of the pad relative shorter hydrophilicfibers.

Thus, another feature of the invention is that the fused materialsprovide a more cohesive pad which has a greater absorbent capacity andloft.

Still another feature of the invention is the provision of feed rollscontaining a compressed web of hydrophobic and hydrophilic materials.

Another feature of the invention is that the hydrophobic materials arefused in the rolls and enhance the structural integrity of the rolls.

A feature of the present invention is the provision of an apparatus anda method for making the articles of the present invention from such feedrolls.

Another feature of the invention is the provision of an apparatus and amethod for making feed rolls from a source of waste or raw materialscontaining bulk hydrophobic and hydrophilic materials.

Yet another feature of the present invention is the provision of anapparatus and a method for controlling the width and basis weight ofsuch feed rolls.

Still another feature of the invention is that the bulk hydrophobic andhydrophilic materials are converted to a form as rolls which may bereadily placed in storage or handled during manufacture of the articles.

Further features will become more fully apparent in the followingdescription of the embodiments of this invention and from the appendedclaims.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary plan view of an absorbent article of the presentinvention, being illustrated in the form of a disposable diaper;

FIG. 2 is a fragmentary sectional view taken substantially as indicatedalong the line 2--2 of FIG. 1;

FIG. 3a and 3b are fragmentary elevational views, partly broken away, ofan apparatus for making feed rolls, utilized in making the absorbentarticles of the present invention, according to a method of the presentinvention;

FIGS. 4a and 4b are fragmentary top plan views, partly broken away, ofthe apparatus of FIGS. 3a and 3b;

FIG. 5 is an elevational view of a portion of a roll winding apparatuswhich is shown in a different configuration from that illustrated inFIGS. 3b and 4b; and

FIG. 6 is a fragmentary elevational view illustrating apparatus formaking absorbent pads for the articles of the present invention from aplurality of feed rolls, according to a method of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although for convenience the articles of the present invention will bedescribed primarily as disposable diapers, it will be understood thatthe articles may be of any suitable type, such as sanitary napkins ormaternity napkins. Also, in the description below, relating tomanufacture of the articles of the present invention from wastematerials, it will become apparent that the finished or new articles maybe made from waste articles of the same type as the finished articles,from waste articles different than the finished articles, or from othersuitable bulk materials.

Referring now to FIGS. 1 and 2, there is shown an absorbent article ordisposable diaper generally designated 20 having a fluid imperviousbacking sheet 22, a fluid pervious cover or top sheet 24, and anabsorbent pad 26 intermediate the backing and cover sheets 22 and 24,respectively, such that the backing sheet 22 covers the back surface 28of the absorbent pad 26, while the top sheet 24 covers at least aportion of the front surface 30 of the pad. As shown, the backing sheet22 may have side margins 32 which are folded over and secured to thesides of the top sheet 24. The diaper may also have a top wadding sheet34 intermediate the front surface 30 of the pad 26 and the cover sheet24, and a back wadding sheet 36 intermediate the back surface 28 of thepad 26 and the backing sheet 22. The wadding sheets 34 and 36 serve tomaintain the structural integrity and prevent balling of the absorbentpad 26 when the pad becomes wet during use.

The diaper 20 may also include a pair of conventional tape fasteners 38.The fasteners 38 may have a backing 40 with adhesive 42 coated on onesurface of the backing. The adhesive 42 on one end 44 of the fasteners38 is attached to the back surface or backing sheet 22 of the diaper,while the adhesive on the other end 46 of the fasteners may bereleasably covered by a release sheet 48. During placement of thediaper, the release sheets 48 are removed from the other ends 46 of thefasteners 38, and the fasteners are utilized to secure the diaper aboutthe infant. The diaper 20 may be utilized in its flat condition asshown, or may be folded into a box-pleat configuration, or othersuitable configuration, as desired.

The materials utilized to make the diaper are described as follows. Thebacking sheet 22 is normally made from a thermoplastic material, such aspolyethylene, while the top sheet 24 is commonly made of a nonwovenmaterial which may include up to 20 percent by weight of a hydrophobicbinder. Accordingly, the backing sheet is made of a hydrophobicmaterial, while a reasonable proportion of the top or cover sheet 24 ismade of a hydrophobic material. The remainder of the nonwoven top sheetis made of a fibrous material. The top and backing wadding sheets 34 and36, respectively, are normally made of an absorbent cellulosic fibrousmaterial. The backings 40 of the fasteners 38 may be made of athermoplastic material, such as polyethylene, or paper, while theadhesive 42 may have an acrylic or rubber base depending upon theparticular characteristics of the adhesive desired. The release sheets48 for the fasteners 38 may be made of suitable paper having a siliconrelease coating to provide a limited affinity of the sheets for theadhesive 42 on the backings 40, and permit ready removal of the releasesheets from the adhesive. The absorbent pads in conventional disposablediapers or articles are frequently made from a fibrous absorbentcellulosic material.

The absorbent pads 26 of the articles or diapers 20 of the presentinvention have a mass of hydrophilic fibers 50 with a mixture ofcomminuted or fiberized hydrophobic materials 52 dispersed throughoutthe pad. The hydrophobic materials 52 form a matrix in interfiber spacesdefined by the hydrophilic fibers 50, and, due to resiliency of thehydrophobic materials although wetted, increase the wet resiliency ofthe pad 26. In the absence of the hydrophobic materials, the hydrophilicfibers are compacted when wetted and placed under loads, thus closinginterfiber spaces between the fibers and impairing the absorbentfunction of the pad. However, the hydrophobic materials dispersed in thepad of the present invention assist in maintaining the interfiber spacesof the hydrophilic fibers open when the pad is wetted and placed underloads, thus preventing collapse of the corresponding interfiber spacesin the wetted pad, and enhancing the absorbent function of the padduring extended use of the article or diaper 20.

Since conventional disposable articles are made from hydrophobic andhydrophilic materials, as discussed above, it will be seen that thematerials of such articles are compatible with the materials required inthe absorbent pads 26 of the present invention. Thus, absorbent articleswhich are normally discarded as waste, resulting from the manufacture offinished articles, may be utilized in the absorbent pads of the presentinvention by selecting suitable quantities of the waste materials formaking the pads. Accordingly, the hydrophilic materials contained in thewaste articles may be formed into at least a portion of the hydrophilicfibers in the absorbent pad 26, while the hydrophobic materials in thewaste articles may be reformed as the hydrophobic materials 52 in thepad 26. As previously noted, the hydrophilic materials for the pad 26may be obtained from the waste absorbent pad, a portion of the waste topsheet, the waste top and back wadding sheets, and possibly the wastebackings of the tape fasteners. The hydrophobic materials for the pad 26may be obtained from the thermoplastic backing sheet, the hydrophobicportion of the top sheet, and possibly the backings of the tapefasteners.

It is, of course, desirable to make maximum use of the valuablematerials contained in such waste articles, and, accordingly, the wastearticles are preferably used, as available, in making the new pads 26,since the materials would otherwise be discarded. When not available, itis apparent that the pads 26 may be made from virgin or nonwastehydrophilic and hydrophobic materials, as desired. It is alsocontemplated that waste articles which contain the pads 26 of thepresent invention may be utilized to make further articles, bycontrolling the relative proportion of the hydrophobic and hydrophilicmaterials in the resulting finished article. The desired structure ofthe absorbend pad 26 in the articles of the present invention,containing relative amounts of hydrophilic and hydrophobic materials toachieve the desired characteristics of the pad, will be described indetail below.

Turning now to FIGS. 3a and 4a, an apparatus 60 is illustrated formaking feed rolls, according to a method of the present invention, whichare utilized in making the absorbent pads 26 for the diapers or articles20 of the present invention. As shown, the apparatus 60 has an endlessconveyor belt 62 supported by a pair of rollers 64a and 64b, with theroller 64b and the belt 62 being driven by suitable drive means 66, suchas a motor. The belt 62 has an extended length, such that sufficientspace is provided for placement of bulk raw materials 68, which areutilized to make the feed rolls, on an uncovered region 70 of the belt62. As previously indicated, the raw materials 68 may be waste materialswhich have been rejected from the manufacturing line, and may bedelivered to the apparatus 60 from the line in extended or relativelyshort lengths, depending upon the condition during manufacture whichcaused rejection of the articles as unpackaged goods. As desired, bulkwaste or virgin hydrophobic and hydrophilic materials may be placed onthe conveyor belt 62 at region 70, either separately or in combination,and in relative amounts to achieve the desired proportions ofhydrophobic and hydrophilic materials in the feed rolls, and ultimatelyin the absorbent pads.

The raw materials 68 are then moved by the belt 62 toward a paddle 72,as indicated by direction of the arrows in the drawings, having aplurality of blades 74. The paddle 72 is rotably driven by drive means76, such as a motor, in a clockwise direction, such that the ends of theblades 74, which are spaced slightly from the belt 62, repetitivelyreturn an excess portion of the materials 68, if any, back toward theplacement region 70 of the belt 62. Accordingly, the paddle 72 andblades 74 serve to limit the quantity of bulk materials which are passedbeneath the paddle 72, in order to maintain the amount of materialstransported to shredding means, described below, in manageablequantities.

The materials 68 which pass beneath the blades 74 of the paddle 72 aretransported by the belt to a pair of spaced rolls 78 which are driven bydrive means 80, such as a motor, in opposite directions, as indicated bythe direction of the arrows in the drawings. The materials 68 thus passinto the nip 82 between the rolls 78, where the materials are held whilea shredder 84 tears the materials into relatively small hydrophobic andhydrophilic particles 85. The shredder 84 may be of any suitable type,such as a device having a plurality of spaced blades 88 mounted on arotable rod 90, with the blades 88 having projecting teeth 92 spacedaround the periphery of the blades. The rod 90 and blades 88 are rotatedby drive means 86 in a counterclockwise direction, such that the teeth92 rip apart or shred the materials retained by the rolls 78, with theshredded particles collecting in a chamber 94 below the blades 88.

As will be seen below, the shredded particles will be later reduced toparticles or fibers of yet a smaller size. For convenience interminology, various terms, such as shredding, fiberizing, andcomminuting, will be used interchangeably to designate a similar result,viz., breaking down and reducing the average size of materials, such aspieces, particles, or fibers, to particles or fibers of an averagesmaller size. This result may be accomplished by suitable apparatuswhich tear apart, shred, rip, pulverize, or perform similar functions.Such apparatus include shredders, hammermills, fiberizers, pincylinders, or other devices of similar nature designated by variousterms in the art.

A closed air transport system 96 is provided for moving the particles 85from the chamber 94 to a cyclone separator 98, while preventing theparticles from escaping to the atmosphere. A blower 100, driven by drivemeans 102 through belts 103, draws the particles from the chamber 94through a connecting conduit 104, and blows the particles through averticle conduit 106 and a horizontal conduit 108 into the separator 98.

As shown in the drawings, the air and particles are moved in a generallycircular or spiral path inside the separator 98, such movement beinginduced by the air arriving in the separator from the blower 100, theair blown by a blower 110 through a conduit 112 into the horizontalconduit 108 and thence the separator 98, and the air driven into thesystem below the separator 98 by a blower 114. As the entrainedparticles of various size are driven in this circular path, the heavierparticles move toward the central region of the separator 98, andeventually settle into a lower chamber 116, where the heavier particlesare collected. At the same time, the residue of lighter particles, suchas powder and dust, move to the outer portion of the circulartrajectory, and eventually pass through a tube 118 to a filter 120,where the residue of lighter particles are collected while the filteredair passes into the atmosphere through an exhaust tube 122.

The heavier particles are thus separated and deposited in the chamber116 adjacent one end of an endless, horizontally disposed, conveyor belt124. The belt 124 has a plurality of spikes 126 projecting outwardlyfrom its outer surface. The spikes 126 may be arranged in lateral rowson the belt with the rows being suitably spaced completely around thelongitudinal periphery of the belt. As shown, the belt is supported by apair of rollers 128a and 128b, with the roller 128b being driven bysuitable drive means 130, such as a motor. The materials or particleswhich are deposited in the chamber 116 collect in a pile on top of andaround the belt 124, and the belt 124 transports the overlying materialstoward an endless belt 132, as indicated by the direction of the arrowin the drawings, which is preferably disposed at an acute angle relativethe vertical direction. Thus, so long as particles are located on theupper reach of the belt 124, the materials are continuously supplied bythe belt 124 to the belt 132. If the particles collect in a considerablepile above the belt 124, the materials adjacent the upper reach of thebelt 124 are dislodged from the pile by the spikes 126, and are movedtoward the belt 132. Since the belt 124 is slightly spaced from thelower end of the chamber 116, as shown, it is apparent that the spikes126 on the lower reach of the belt serve to remove materials from belowthe belt for subsequent transportation to the belt 132.

The belt 132 is supported by a pair of rollers 134a and 134b, and has aplurality of spikes 136 projecting outwardly from its outer surface in aconfiguration similar to that described in connection with the belt 124.The belt 132 is driven by suitable drive means 136, such as a motor, ina clockwise direction, as viewed in the drawings, such that theparticles suppled by the belt 124 are lifted by the spikes 136 towardthe upper turn of the belt 132. Thus, movement of the belts 124 and 132result in a supply of particles at the upper turn of belt 132, for apurpose described below. If a substantial pile of materials havecollected in the chamber 116, a general shifting of the pile toward theupper turn of belt 132 will take place.

As shown in the drawings, a portion of the particles which are lifted bythe belt 132 pass over the upper turn of belt 132 to the nip 142 betweena pair of rolls 138. However, an endless belt 146, which is supportedhorizontally by a pair of rollers 148a and 148b, returns an excessportion of the particles lifted by belt 132 for subsequent conveyance.The roller 148b and belt 146 are driven by drive means 149, such as amotor, in a clockwise direction, as indicated by the direction of thearrow in the drawing. As shown, the right turn of belt 146 is spacedslightly from the belt 132 adjacent the upper turn of belt 132. Thus, aplurality of spikes 150 projecting outwardly from the belt 146, whichmay be arranged as described in connection with the spikes on belt 124,remove an excess quantity of materials from the belt 132, and drop theexcess particles on the particle collection above the belt 124 forsubsequent transport to the belt 132. At the same time, the belt 146permits a limited quantity of particles to pass to the upper turn ofbelt 132. Thus, the belts 146 and 132 co-operate to limit the quantityof particles supplied to the rolls 138. It will be apparent that thequantity of materials supplied to the rolls 138 may be controlled by therelative spacing between the belts 146 and 132, and by the rotationalspeeds of the various belts 124, 132, and 146.

The rolls 138 are driven in opposite rotational directions, as indicatedby the direction of the arrows in the drawings, by suitable drive means140, such as a motor. Thus, the particles supplied by the belt 132 atthe nip 142 of the rolls 138 are passed through the nip to a fiberizer152, such as a pin cylinder. It will be apparent that the quantity ofmaterials supplied by the rolls 138 to the fiberizer 152 may becontrolled, in part, by the spacing between the rolls 138 and by therotational speed of the rolls.

The fiberizer 152 is driven in a clockwise direction by suitable drivemeans 154, as indicated by the direction of the arrow in the drawing,and reduces the particles passing from rolls 138 into a finer size asrelatively small particles, shreds and fibers, including hydrophobic andhydrophilic materials. The fiberizer 152 also deposits the comminutedparticles or fibers at a location 162 on the upper reach of an endlessscreen 156 as a fibrous mass. The screen 156 is supported by a pair ofrollers 158a and 158b, with the screen 156 and roller 156b being drivenin a clockwise direction by suitable drive means 160, such as a motor,such that the fibrous mass deposited on the screen is continuouslytransported away from the location 162, with the fibrous mass beingformed as a fibrous layer or web 163 on the upper reach of the screen156.

The blower 110 is connected through a conduit 164 to a vacuum inletplate 166 which is supported beneath the upper reach of screen 156 inthe region of location 162, and serves as a source of vacuum supplied tothe fibrous web through conduit 164, plate 166 and the screen 156. Thus,air is drawn through the screen into the plate 166 throughout alongitudinal region of the screen at location 162 due to elongation ofthe plate along the screen, and the vacuum source thus draws the fibrousmass passing from the fiberizer 152 against the screen. It will beapparent that the thickness of the fibrous web 163 formed on the screen156 is partly determined by the rotational speed of the screen 156,since a greater thickness of fibers will be collected on the screen forslower speeds of the screen, while a lesser thickness of the fibers willcollect at a given location on the screen responsive to relativelyhigher speeds of the screen. Also, the thickness of the web formed onthe screen 156 may be controlled by the blower 110, with a greatersource of vacuum drawing an additional amount of fibers onto the screen,resulting in a thicker web on the screen. As will be seen below, therelative thickness of the web formed on the screen 156 ultimatelydetermines the basis weight of the feed rolls formed by the apparatus60. Thus, the thickness of the web 163 and basis weight of the feedrolls may be controlled in various manners, as described above, bymaking suitable modifications to the following: (a) the rotationalspeeds of belts 124, 132, and 146; (b) the spacing between belts 132 and146; (c) the rotational speeds and spacing of rolls 130; (d) therotational speed of screen 156; and (e) the vacuum source of blower 110.

An excess of fibers from the web 163 may pass into the plate 166 due tothe vacuum supplied by the blower 110. Such fibers pass through theconduit 164, the blower 110, and the conduit 112 into the horizontalconduit 108 and the separator 98, where they are again separated intoheavier and lighter particles, as previously described. As the fibrousweb 163 on the screen 156 is transported away from the fiberizer 152 andlocation 162, as shown in the drawings, any excess or loose particles orfibers from the web are removed by a relatively slight vacuum sourcesupplied by the blower 114 through a conduit 170 to a vacuum inletmember 168, which is spaced slightly from the web 163 laterally acrossthe screen. The vacuum source is sufficiently small to prevent removalof the web 163 from the screen 156, and the loose fibers are transportedby the source through the conduit 170 and blower 114 to the chamber 116for subsequent passage to the fiberizer 152.

As illustrated in FIGS. 3a, 3b, 4a, and 4b, the fibrous web 163 istransported by the screen 156 onto an endless belt 172 which has asomewhat greater slope in the vertical direction. As illustrated inFIGS. 3b and 4b, the belt 172 is supported by a pair of rollers 174a and174b, with the roller 174b and belt being driven by suitable drive means176, such as a motor, in a clockwise direction, such that the fibrousweb 163 is moved toward the upper turn of the belt 172, as indicated bythe direction of the arrows in the drawing. A spraying device 178 spraysa liquid, such as water, onto the fibrous web 163 as it is moved on thebelt 172, in order to wet the web and facilitate integration of itsfibers during a subsequent calendering procedure, as will be describedbelow.

The fibrous web 163 then passes between a pair of aligned and slightlyspaced endless belts 130 and 182 which compress the web and reduce itsloft. The belt 180 is supported by a pair of rollers 184a and 184b,while the belt 182 is supported by a pair of rollers 186a and 186b, withthe rollers 184b and 186b and webs being rotably driven in oppositedirections by suitable drive means 188, such that the web is transportedthrough the spacing between the webs 180 and 182 while being compressed.

A web 190 of tissue is unwound from a roll 192 supported on a stand 193,and passes over a roller 194 to a location intermediate the fibrous web163 and the belt 182, such that the tissue web 190 is placed against onesurface of the fibrous web 163. If desired, a second web 196 of tissuemay be placed against the opposing surface of the fibrous web 163, asshown, with the web 196 being unwound from a roll 198 and being passedover a roller 200 to a location intermediate the fibrous web 163 and thebelt 180. Thus, the web 163 may be placed on a single tissue 190, or maybe placed between the tissues 190 and 196, as desired. In either event,the tissue web means serves as a carrier and surface structure for thefibrous web 163 after it passes from the belts 180 and 182.

As shown, the compressed or compacted fibrous web passes through the nip210 between a pair of metal rolls 204 and 206 in a calender 202. Thecalender rolls 204 and 206 are driven in opposite rotational directionsby suitable drive means 208, as indicated by the direction of the arrowsin the drawings. The rolls 204 and 206 are also heated by a suitablemeans 211, such as a heat transfer system for each roll utilizing hotoil to generate the desired temperatures at the surfaces of the rolls.

Thus, the fibrous web is simultaneously heated and compressed by thecalender rolls 204 and 206 as it passes through the nip 210 of thecalender 202 resulting in formation of a compacted web passing from thecalender. It will be recalled that compaction of the fibers in the webis facilitated by the liquid added to the web by the spraying device178. Also, since a portion of the hydrophobic materials in the fibrousweb are preferably thermoplastic, the heated rolls 204 and 206 fuse thethermoplastic hydrophobic materials in the compressed web and bind thefibers together to provide structural integrity for the compressed webin addition to that provided at the surface of the compressed web by thetissue web 190 or webs 190 and 196.

The compressed or compacted web is then passed around the outer surfaceof roll 206 to a second calender 212 where the web is again heated andfurther compressed. As shown, the calender 212 has a pair of rolls 214and 216 which are driven in opposite rotational directions by suitabledrive means 218. The rolls 214 and 216 are also heated by the heatingmeans in a manner as described in connection with the calender 202. Ifdesired, the calenders 202 and 212 may be operated at differenttemperatures, and, in a configuration found suitable, the surfacetemperature of the rolls 204 and 206 of calender 202 may beapproximately 190° to 300° F., while the surface temperature of therolls 214 and 216 of calender 212 may be approximately 300° to 400° F.

The compressed web then passes from the nip 220 of rolls 214 and 216 toa knife-over-roll device 221 where the web may be slit, if desired. Asshown, the device 221 has a roller 222 which provides a supportingsurface for the web while it is slit. The device 221 also has a rotablymounted blade 224 which may be moved into position against the web toperform the slitting operation. The blade 224 may be selectively movedto a vertical location spaced from the web, as indicated by the arrowsin the drawings, by suitable means if it is undesired to slit the web.As will be seen below, when the web is slit by device 221 a plurality offeed rolls are simultaneously formed, while a single feed roll is formedif the web is not slit. It is apparent that more than two webs may beformed, as desired, by providing a suitable number of knife-over-rolldevices, or other cutting means, spaced laterally across the web.

The apparatus 225 for winding feed rolls is described as follows. Theapparatus 225 has a pair of laterally spaced fork members 232 pivotallymounted on a table 240 by pivotal supports 234. The fork members 232 maybe moved between an upright position while formation of a feed roll isinitiated, as shown in FIGS. 3b and 4b, and horizontal position during alater stage of the winding procedure, as shown in FIG. 5. The apparatus225 has a plurality of mandrels 226 on which the feed rolls are wound.As illustrated in FIGS. 3b and 4b, each of the fork members 232 has apair of tines 230 to receive the ends of the winding mandrels 226 whilethe fork members are in an upright position. Subsequently, the ends ofthe mandrels 226 are supported on a surface 238 provided by a pair ofspaced arms 239 in the table 240. The apparatus also has a resilientsurface winding roll 236 which is mounted for rotational movement anddriven in a clockwise direction by suitable drive means 242.

The formation of feed rolls by the apparatus from the compressed web isdescribed as follows. If the web has been slit by the device 221, aplurality of paper cores 228 corresponding to the widths of the slitwebs are placed on a mandrel 226. If the web has not been slit, a singlepaper core may be positioned on the mandrel 226. Next the fork members232 are placed in their upright position, as shown in FIGS. 3b and 4b,and the mandrel 226 containing the core or cores 228 is positioned inthe tines 230 of the fork members, while the end of the compressed webor slit webs is wound in a counterclockwise direction around the papercore or cores one or more turns, such that the web is positionedintermediate the mandrel and the surface winding roll 236.

As shown, the openings defined by the tines 230 are sufficiently deep topermit the mandrel 226 to bear against the winding roll 236.Accordingly, the outer surface of the winding roll 236 frictionallyengages the web, and surface movement of the roll 236 is imparted to theweb and mandrel 226 through the core or cores 228. Since the mandrel ispermitted to rotate in the tines 230, the rotational movement of thewinding roll 236 in the clockwise direction results in a correspondingcounterclockwise rotation of the mandrel 226 while the web is wound onthe mandrel. As the web is thus surface wound onto the mandrel, thediameter of the new feed roll on the mandrel is gradually increased,such that the distance between the mandrel and the winding roll 236 isincreased. However, the new feed roll continues to bear upon the outersurface of the winding roll 236, thus maintaining frictional engagementbetween the outer surface of the winding roll 236 and the web, resultingin initial formation of the feed roll while the mandrel 226 risesrelative the winding roll 236.

Prior to the time at which the mandrel 226 is located at a positionabove the tines 230, a completed feed roll 244, which has the ends ofits mandrel 226 resting on the support surface 238, is removed from thetable 240 for storage and subsequent use. After the feed roll 244 hasbeen removed, the fork members 232 are moved to their horizontalposition, as shown in FIG. 5, such that the mandrel 226 of the new feedroll 246 rests upon the support surface 238 of the table 240. In thisconfiguration, the tines 230 of the fork members are located in aposition to permit freedom of movement and rotation of the mandrel 226along the support surface 238.

Additionally, the new feed roll 246 continues to bear against the outersurface of the winding roll 236, such that frictional engagement betweenthe web and the winding roll is maintained, resulting in a continuedsurface wind of the feed roll 246 while the feed roll and mandrel 226rotate in a counterclockwise direction. As the diameter of the feed roll246 increases, the axis of the mandrel is displaced toward the right ofthe table 240, as viewed in the drawing. After a sufficient length ofthe web has been surface wound onto the mandrel, the web is severedtransversely across the web, the fork members 232 are again pivoted totheir upright position, as previously described in connection with FIGS.3b and 4b, another mandrel is placed in the tines, formation of a newfeed roll is initiated, and the completed feed roll is removed from thetable. It is apparent that if the web was slit into a plurality of websby the device 221, a corresponding number of feed rolls aresimultaneously formed on their respective paper cores.

Thus, feed rolls are made by the apparatus 60 from an initial supply ofbulk hydrophilic and hydrophobic materials. The waste materials areconverted into a compressed web containing the hydrophobic andhydrophilic materials, and the compressed web is wound into feed rollsfor convenience in handling during storage and subsequent use for makingarticles of the present invention, as described below.

According to a method of the present invention, a source of waste orbulk hydrophobic and hydrophilic materials is thus shredded by ashredder into particles, while limiting the quantity of the materialssupplied to the shredder. The shredded particles are transported by airfrom a first shredding location to a second separating location wherethe lighter and heavier particles are separated. The shredded particlesare moved by air in a generally circular path, the lighter particles areremoved from the path and are discarded, and the heavier particles arecollected.

The collected heavier particles are transported to a fiberizer, wherethe particles are comminuted or fiberized into a fibrous web containinga mixture of hydrophobic and hydrophilic materials, while limiting thequantity of particles supplied to the fiberizer. The comminutedparticles passing from the fiberizer are placed on a movable memberwhich provides an endless supporting surface at the location ofplacement, while moving the member relative the location to form a layeron the member as the fibrous web.

The comminuted particles are drawn against the member with a source ofvacuum, and the thickness of the fibrous web may be controlled bycontrolling the vacuum source to control the rate at which the particlesare drawn against the member by the source. The thickness of the fibrousweb may also be controlled by controlling the rate of movement of themember relative the location by placement on the member. Excess fibersmay be returned from the fibrous web to the circular path or to thecollection of heavier particles.

Next, the fibrous web is wetted and placed against a carrier web, afterwhich the web is compressed to reduce its loft. The web is thensimultaneously heated and compressed one or more times to produce acompressed web in which the thermoplastic hydrophobic fibers are fused.The compressed web is wound into feed rolls subsequent to a slittingprocedure, if desired, to vary the width of the feed rolls formed.

An apparatus 258 for utilizing the completed feed rolls 244 for makingthe absorbent pads of the present invention containing a mixture ofhydrophilic and hydrophobic fibers will be described in connection withFIG. 6. As shown in the drawing, the completed feed roll 244 issupported for rotational movement, such that the compressed web may beunwound from the roll 244 and passed into a fiberizing or comminutingapparatus 250, such as a hammermill. One or more additional feed rolls252 containing a compressed web or virgin hydrophilic materials may alsobe supported for rotational movement, in order that their webs may beunwound and passed into the apparatus 250 which simultaneouslycomminutes the compressed webs from the feed rolls 244 and 252. Theapparatus thus reduces the webs to fibers or particles of hydrophobicand hydrophilic materials, and forms a fibrous web 254, which is passedonto an endless conveyor belt 256, supported and driven by a pair ofrollers 258a and 258b. A carrier web 260, such as cellulose wadding, isunwound from a roll 262, passed over a roller 264, and placed againstthe fibrous web 254 at a location intermediate the web 254 and belt 256.The fibrous web 254 and carrier web 260 are then transported by the belt256 to an apparatus 266 of known type which cuts and forms the webs intosections as absorbent pads. The pads, containing a mixture ofhydrophobic and hydrophilic materials, are then made into suitabledisposable articles or diapers, as desired.

Thus, the feed roll 244 may be used in conjunction with feed rollscontaining soley hydrophilic materials to form a fibrous web which iscut into sections as absorbent pads for the articles of the presentinvention. It will be apparent that the relative proportion of thehydrophobic and hydrophilic materials contained in the pads may bedetermined in a number of manners. Initially, the relative amounts ofthe webs from the feed roll 244 and the remaining feed rolls 252pulverized by the apparatus 250 may be controlled by the number ofhydrophilic feed rolls 252 utilized simultaneously in conjunction withfeed roll 244. Also, the width of the feed roll 244 relative the widthof the feed rolls 252 may be controlled by the slitting device 221described in connection with FIGS. 3b and 4b. Thus, varying widths offeed roll 244 relative a given width of the rolls 252 will result incorresponding varying proportions of the feed roll 244 and hydrophobicmaterials being introduced into the fibrous web 254 and absorbent pads.

Additionally, as described in connection with FIGS. 3a and 4a, thethickness of the fibrous web 163 formed on the screen 156 may besuitably modified to control the thickness and basis weight of thecompressed web which is formed into the feed rolls. Thus, as shown inFIG. 6, the thickness of the compressed web from the feed roll 244relative a given thickness of the webs in rolls 252 will also determinethe relative amount of hydrophobic materials introduced into the fibrousweb 254 and absorbent pads. Finally, the relative amounts of hydrophobicand hydrophilic materials introduced into the feed roll 244, and thusthe pads, may be controlled by determining the relative proportions ofhydrophobic and hydrophilic materials placed on the belt 62 as thesource of raw material 68, as described in connection with FIGS. 3a and4a.

Although the bulk raw materials 68 may be obtained from any suitablesource, it is desirable to primarily utilize for this source thosematerials or articles which were previously rejected as waste from themanufacturing line. Accordingly, for convenience in discussion below theraw materials 68 will be designated as waste articles, and the variouscomponents which constitute the waste article will be preceded by theterm "waste", e.g., waste backing sheet, and waste absorbent pad. Thehydrophilic and hydrophobic materials contained in the web of the feedroll 244, described in connection with FIG. 6, may be termed "waste feedmaterial", while the hydrophilic material contained in the feed rolls252 will be called "virgin feed material". The newly formed absorbentpads containing a mixture of hydrophobic and hydrophilic materials willbe designated a "new absorbent pad" or "new pad", while the completedabsorbent article or diaper containing the new pad will be termed the"new absorbent article" or "new diaper", with the components of the newarticle being preceded by the word "new", e.g., new backing sheet.

Since the waste articles are converted to the waste feed material, therelative proportion of the waste components contained in the wastearticle will be similar to that contained in the waste feed material.Accordingly, the relative amounts of hydrophobic and hydrophilicmaterials contained in the waste feed material will be similar to theproportion of the same materials contained in the waste articles. Sincethe relative amounts of the waste and virgin feed materials introducedinto the new absorbent pads may be determined, the proportion ofhydrophobic and hydrophilic materials contained in the new pad orarticle may also be calculated.

As noted above, the various components of the waste article, such as thewaste backing sheet or pad, may be classified generally as being ahydrophobic or hydrophilic material, or as a material containing a knownproportion of hydrophobic and hydrophilic materials, such as the topsheet. Accordingly, in determining the relative amounts of hydrophobicand hydrophilic materials in the new absorbent pads, it is convenient tofirst calculate the relative quantities of the waste componentsintroduced into the new pads or articles, which may be accomplishedaccording to the following formulae:

    W.sub.cn =(W.sub.tcn)[W.sub.cw)/(W.sub.tw)],               (1)

where,

W_(cn) =Weight of a particular waste component in a new article;

W_(tcn) =Total weight of waste components in the new article;

W_(cw) =Weight of the same component (W_(cn)) in the waste article; and

W_(tw) =Total weight of waste article.

However, since

    W.sub.tcn =(W.sub.tpn)[(W.sub.tcn)/(W.sub.tpn)],           (2)

then

    W.sub.cn =(W.sub.tpn)(P.sub.tcn)[(W.sub.cw)/(W.sub.tw)],   (3)

where,

W_(tpn) =Total weight of new absorbent pad; and

P_(tcn) =(W_(tcn))/(W_(tpn))=proportion of waste and total materials inthe new pad, or proportion of waste feed materials and total feedmaterials introduced into the new pad.

Additionally,

    P.sub.cn =[(W.sub.cn)(100)]/(W.sub.tpn),                   (4)

where

P_(cn) =Percentage by weight of the waste component in the new padrelative the total weight of the new pad.

As an illustration, standard size waste diapers having a total weight of33.5 grams may be utilized to make the new absorbent pads for thearticles or diapers of the present invention. The weight of the variouscomponents in each waste diaper is set forth in the following table:

                  TABLE I                                                         ______________________________________                                        Component           weight (grams)                                            ______________________________________                                        Absorbent Pad       21                                                        Top Sheet           2.7                                                       Backing Sheet       4.2                                                       Tape Fasteners      1.1                                                       Wadding Sheets      4.5                                                       ______________________________________                                    

The percentage of waste feed materials relative the total amount of feedmaterials introduced into the new pad is selected to be 12 percent, andthe weight of the new absorbent pads are also 21 grams. Accordingly, theweight of a given waste component, say the backing sheet, may becalculated from formula (3) as follows: ##EQU1## Thus, the weight of thewaste backing sheet contained in the new absorbent pad is 0.316 grams.It will be apparent that the percentage by weight of the waste backingsheet in the new absorbent pad is 1.5 percent, as determined by formula(4).

The weights and percentages of the various waste components in the newpad may be determined in a similar fashion, and are set forth in thefollowing table:

                  TABLE II                                                        ______________________________________                                                   Weight in  Weight in Percentage                                               Waste Article                                                                            New Pad   of Component                                  Component  (grams)    (grams)   in New Pad                                    ______________________________________                                        Absorbent Pad                                                                            21         1.580     7.52                                          Top Sheet  2.7        .203      .97                                           Backing Sheet                                                                            4.2        .316      1.50                                          Tape Fasteners                                                                           1.1        .083      .40                                           Wadding Sheets                                                                           4.5        .339      1.61                                          Total      33.5       2.521     12.00                                         ______________________________________                                    

It will be seen that the total weight of the waste components in the newpad is 2.521 grams, and that the percentage of total waste components inthe new pad is 12 percent, as expected.

The relative quantities of hydrophobic and hydrophilic materials in thenew pad may be readily determined as follows. Assuming that the wastetape fasteners have a polyethylene backing, the new absorbent pad willinclude approximately 0.083 grams of hydrophobic material, ascontributed by the fasteners including adhesive. Next, it is assumedthat the waste top sheet contains 20 percent by weight of a hydrophobicbinder, while the remainder of the top sheet is made of a hydrophilicmaterial. Thus, it may be determined in connection with Table II thatthe weight of the hydrophobic portion of the top sheet contained in thenew pad is 0.041 grams. Finally, the weight of the hydrophobic backingsheet in the new pad has been determined as 0.316 grams. Accordingly,the total weight of hydrophobic materials in the new pad is theresulting sum of 0.440 grams, while the remainder of the new pad iscomposed of hydrophilic materials, including waste and virgin feedmaterials, and has a weight of 20.56 grams. Thus, the percentage byweight of the hydrophobic materials in the new pad to the total weightof the pad is approximately 2.1 percent, while the percentage by weightof hydrophilic materials in the new pad is approximately 97.9 percent.It will be apparent that the percentage by weight of the virginhydrophilic feed materials in the new pad to the total weight of the padis 88 percent with the weight of the virgin materials contained in eachof the new pads being approximately 18.48 grams.

As previously discussed, it is desired to place a sufficient amount ofthe hydrophobic materials in the new pad such that the wet resiliency ofthe new pads or articles when placed under loads is increased, althoughthe relative quantity of the hydrophilic materials in the new pad shouldnot be decreased to an extent at which the total absorptive capacity ofthe pad is impaired. It has been found that a suitable balance betweenthe hydrophobic and hydrophilic materials in the new pad to achievethese functions may be obtained by selecting the proportion by weight ofthe hydrophobic materials in the new pad to the total weight of the padto be in the range of 1 to 15 percent, while the proportion of thehydrophilic materials by weight is in the corresponding range of 85 to99 percent. Although the proportions of the waste components containedin a given waste article will vary somewhat depending on the structureof the article, the preferred proportions of the waste components froman average sized disposable diaper placed in the new pad of a similardiaper, as determined by the ratio of the waste component weight in thenew pad to the total weight of the new pad, is set forth as follows:waste absorbent pad, 3.5 to 17.0 percent; waste top sheet, 0.5 to 2.5percent; waste backing sheet 1.0 to 3.0 percent; waste tape fasteners0.1 to 1.0 percent; and waste wadding sheets 1.1 to 3.2 percent. Apreferred proportion by weight of the waste feed material to the totalfeed materials is in the range of 5.0 to 25.0 percent, while thecorresponding proportion by weight of the virgin feed materials to thefeed materials is in the range of 75.0 to 95.0 percent.

Thus, there has been described a new and improved absorbent article ordiaper having an absorbent pad comprising a mixture of fibrous orcomminuted hydrophobic and hydrophilic materials, in order to increasethe wet resiliency of the pad and article under loads and improve theabsorbency of the pad during use. Particularly where the waste articlesare disposable diapers, the wet resiliency of the new pads is enhancedby the relative thickness of the waste backing sheet which is normallygreater than or equal to approximately 1 mil. Apparatus and methods arealso provided for making feed rolls from bulk or waste raw materials,and for making the absorbent pads or articles of the present inventionfrom the feed rolls.

Additionally, when the hydrophobic materials are formed into the newpads, these materials provide the new pads with an increased number ofpad materials with longer lengths. Moreover, the thermoplasticmaterials, such as polyethylene, are fused into the feed rolls beforethese materials are comminuted into the new pads. When the fusedmaterials are comminuted along with relatively short hydrophilic fibersin the feed roll, the effective fiber length is increased to a greaterextent than such a mixture with non-fused hydrophobic materials which isbelieved attributable to fusing of the thermoplastic materials to thehydrophilic fibers without completely destroying the hydrophobicthermoplastic particles. The longer fibers thus formed produce a padwith increased structural integrity, and greater absorbent capacity andloft.

The foregoing detailed description is given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

We claim:
 1. The method of making a disposable absorbent pad comprisingthe steps of:collecting a quantity of raw materials including bothhydrophilic and hydrophobic materials, said hydrophobic materials beingat least in part thermoplastic sheet material; simultaneouslycomminuting said raw materials together to provide a mixture ofnon-fibrous hydrophobic particles and hydrophilic fibers; forming saidmixture of particles and fibers into a fibrous web comprising a mass ofsaid hydrophilic fibers and a matrix of said non-fibrous hydrophobicparticles dispersed throughout said web in interfiber spaces defined bysaid fibers; simultaneously heating and compressing said web to fusesaid hydrophobic particles to said hydrophilic fibers without completelydestroying said particles; winding said web into a feed roll; providinga second feed roll containing compressed hydrophilic materials;unwinding webs from said first and said second feed rolls;simultaneously comminuting portions of said webs into a fibrous mass;and, forming said fibrous mass into sections as pads, said unwinding andsimultaneous comminuting being controlled such that said pads include 1to 15 percent by weight said non-fibrous hydrophobic particles and 85 to99 percent by weight said hydrophilic fibers.
 2. The method of claim 1wherein said thermoplastic sheet material is a backing sheet having athickness greater than or equal to 1 mil.
 3. The method of claim 1wherein said raw material includes a comminuted waste absorbent articlewhich includes a hydrophobic sheet material.
 4. The method of claim 1wherein said heating and compressing step comprises the step ofcalendering said fibrous web.
 5. The method of claim 4 wherein saidcalendering step comprises the steps of simultaneously compressing andheating the fibrous web with a first calender at a first temperatureinto a compacted web, and simultaneously compressing and heating thecompacted web passing from the first calender with a second calender ata second temperature into said compressed web.
 6. The method of claim 1including the step of wetting said fibrous web with a liquid before saidcompressing and heating step.
 7. The method of claim 1 wherein said newmaterials are shredded by a shredder and including the step of limitingthe quantity of said materials supplied to the shredder.
 8. The methodof claim 7 including the step of separating the lighter and heavier ofthe shredded particles.
 9. The method of claim 8 including the steps ofdiscarding the lighter of said particles, and collecting the heavier ofsaid particles.
 10. The method of claim 1 wherein said quantity of rawmaterials is in the range of 5 to 25 percent waste feed material and 75to 95 percent virgin feed material, said waste feed material includingsaid thermoplastic sheet material.